Armature-core



(No Model.)

J. J. WOOD. ARMATURE GORE.

'Patente Nov. 20, 1894.

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UNITED STATES ATENT Futon.

JAMES J. WOOD, OF FORT WAYNE, INDIANA.

ARMATURE-CORE.

SPECIFICATION forming part of Letters Patent No. 529,437, dated November20, 1894.

Application filed August 21, 1894. SeriaLNo. 520,881- (No model.)

To all whom it may concern:

Be it known that 1, JAMES J. WOOD, a citizen of the United States,residing at Fort Wayne, Allen county, State of Indiana, have inventedcertain new and useful Improvements in Armature-Cores, of which thefollowing is a specification.

This invention relates to an improved construction of laminated armaturecores for dynamo electric machines or electric motors. Heretofore suchlaminated armature cores have been built up of blanks of sheet ironeither cut out in the form of a complete ring and punched with holesthrough which to pass the fastening bolts of the spider, or they havebeen built up of laminated segmental blanks or punchings united to thespider either by being formed with dove tails on their inner sidesinterlocking with dove tails in a cast metal wheel, or punched withholes through which to pass the fastening bolts of the spider. The useof circular or ring shaped blanks is advantageous in avoiding joints andsaving the necessity of passing fastening bolts through holes in thelaminated cores, as each ring or lamina resists in itself thecentrifugal force, but this construction is expensive because of thenecessity of making an excessivel y large die for punching the ring andbecause of the waste of material from the corners and centers of therectangular sheets of iron from which the rings are punched. Oores forall very large armatures, however, must of necessity be made ofsegmental blanks, since it is impossible to get iron in large enoughsheets from which to cut the complete rings, and it is practically ofgreat importance to secure the best construction for such segmentalcores. The segmental constructions heretofore used have been defectivein not providing for effective heat radiation from the core and in theliability to the generation of Foucault currents. Where the blanks orpunchings are dove tailed to an inner cast metal ring or wheelconsiderable expense is involved in the fitting, the radiation of heatfrom the core is interfered with, and Foucault currents are liable to begenerated in the metal wheel. Where bolts are passed through thelaminated iron core they are required to be insulated in order toprevent the generation of currents in them, and the insulation in courseof time disintegrates and allows the armature core to become loose.

According to the improved construction provided by my invention I buildup the core of segmental blanks or punchings and connect them to thespider by fastening bolts arranged entirely within the body of the core,the sole engagement of the laminated core with the bolts being by meansof curved ears or hooks formed on the inner sides of the sheet ironblanks and projecting inwardly and overhanging the bolts to the extentof about half the diameter of the latter. The centrifugal force is thusresisted by the engagement of these ears or hooks with the bolts. Eachblank has two such ears or hooks which overhang two adjoining boltsengaging the latter on opposite sides so that the two bolts standbetween two ears, whereby the springing outward of the bolts undercentrifugal force is prevented since the respective blanks serve thus asties for linking the respective pairs of bolts together, and as thealternated layers engage (lilferent pairs of bolts the entire structureis efiectively united. By this means also ventilating spaces are formedbetween the respective projecting ears or hooks, which contribute to theradiation of heat from the core.

Figure 1 of the accompanying drawings is an end elevation of an armaturecore constructed according to my invention partly broken away ordissected to show the'details of construction. Fig. 2 is a transversediametrical section of the armature core and spider. Fig. 3 is a plan ofone of the sheet metal blanks or punchings. Fig. 4 is a fragmentarysection showing the engagement of the superposed blanks or punchingswith one of the fastening bolts. Fig. 5 is a fragmentary edge view ofthe same.

Referring to the drawings, A designates the armature shaft; B B, theopposite supporting heads or rings constituting the spider; O O, thefastening bolts, and D the laminated iron core.

The core D is built up of blanks or punchings d of sheet iron such asthat shown in Fig. 3. Each blank constitutes a segment of the completering forming the core, being a third, quarter, or other convenientdivision thereof. The exterior of the blank may or may not be formedwith notches or grooves to form teeth for armature cores as may berequired according to the type of armature to be made. In Fig.3 theblank is shown as thus toothed, while in Fig. 4. it is shown plain oruntoothed. Each blank is formed with two hook-shaped ears or hooks a a.projecting from its inner side and spaced sufficiently apart to overhangor partly embrace two successive bolts G C. In building up the core fromthese punchings or blanks they are alternated so as to break joints, thejoints between the blanks constituting one layer coming opposite themiddles of the blanks constituting the adjoining layers. By means ofthis alternation the hooks a a engage alternately opposite sides of eachof the bolts 0 in the manner clearly shown in Figs. 4c and 5, where itis seen that one-half of the bolt is embraced by the hooks on what I maycall even numbered punchings, while the opposite half of the bolt isengaged by the hooks of intervening or odd numbered punchings. Thus eachof the hooks or projecting ears is separated from its lateral neighborsby an air space equal to the thickness of the sheet from which thepunehings are made and these air spaces contribute greatly to thecooling of the core by radiation. Each of the hooks forms thusessentially a half eye for engaging the bolt, which has the advantageover a full or complete eye, that it does not afford a path for magneticlines of force to encircle the bolt, which would tend to give rise toelectrical currents through the bolts.

The books might be otherwise arranged to engage the bolts in differentways from that shown, but the construction shown is preferable to anyother arrangement for the reason that with hooks otherwise engaging thebolts the centrifugal force would be resisted solely by the stiffness orstrength of the bolts, which would be liable to spring and permit thecore to become distorted by an outward displacement or bulging of thelaminae; but by forming the punchings as shown in Fig. 3 with the hooksarranged to engage the outer or remote sides of the two bolts andcurving toward each other the punching or blank becomes a tie to bindthe two bolts together so.

or no strain is thrown upon the belts or spiders, the sole function ofwhich is thus reduced to carrying the core and resisting the torque.

My invention consequently has the following advantages:

First. There is little or no tendency to generate current in the bolts.

Second. There is greatly increased ventilating surface due to the hookswhich engage the bolts.

Third. The construction is very economical since the waste of iron inmaking the punchings is reduced to the minimum.

Fourth. The punchings when assembled tend to hold each other and tie theentire structure together so that no greater strain is thrown upon thespider than if the punchings constituted complete rings.

Fifth. The mechanical construction is the simplest possible, requiringno heavy spiders and no expensive planing or fitting, but a more easyslipping together of the punchings over the fastening bolts.

I claim as my invention the following-defined novel features,substantially as hereinbefore specified, namely:

1. A laminated armature core built up of alternated segmental blankshaving hooks for overhanging the fastening bolts of the spider, thehooks of alternate laminae embracing said bolts from opposite sides.

2. In an armature the combination with a spider and aseries of parallelfastening bolts, of the laminated core built up of alternated segmentalblanks having each two hooks curved toward each other and overhangingtwo bolts by embracing their relatively remote sides, the blanks ofalternated layers embracing different pairs of bolts, whereby the boltsare tied together by the blanks.

3. A sheet-iron blank for an armature core, consisting of a segment ofthe core having on its inner side overhanging hooks for embracing thefastening bolts.

4. A sheet-iron blank for an armature core, consisting of a segment ofthe core having on its inner side two opposed hooks curved toward eachother, adapted to overhang two fastening bolts by embracing theirrelatively remote sides.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

JAMES J. XVOOD.

Witnesses:

K. STEINBRUNNER, CHAS. J ONES.

